55,006 research outputs found
Lattice Simulation of Nuclear Multifragmentation
Motivated by the decade-long debate over the issue of criticality supposedly
observed in nuclear multifragmentation, we propose a dynamical lattice model to
simulate the phenomenon. Its Ising Hamiltonian mimics a short range attractive
interaction which competes with a thermal-like dissipative process. The results
here presented, generated through an event-by-event analysis, are in agreement
with both experiment and those produced by a percolative (non-dynamical) model.Comment: 8 pages, 3 figure
On Galois-Division Multiple Access Systems: Figures of Merit and Performance Evaluation
A new approach to multiple access based on finite field transforms is
investigated. These schemes, termed Galois-Division Multiple Access (GDMA),
offer compact bandwidth requirements. A new digital transform, the Finite Field
Hartley Transform (FFHT) requires to deal with fields of characteristic p, p
\neq 2. A binary-to-p-ary (p \neq 2) mapping based on the opportunistic
secondary channel is introduced. This allows the use of GDMA in conjunction
with available digital systems. The performance of GDMA is also evaluated.Comment: 6 pages, 4 figures. In: XIX Simposio Brasileiro de Telecomunicacoes,
2001, Fortaleza, CE, Brazi
Numerical study of a model for non-equilibrium wetting
We revisit the scaling properties of a model for non-equilibrium wetting
[Phys. Rev. Lett. 79, 2710 (1997)], correcting previous estimates of the
critical exponents and providing a complete scaling scheme. Moreover, we
investigate a special point in the phase diagram, where the model exhibits a
roughening transition related to directed percolation. We argue that in the
vicinity of this point evaporation from the middle of plateaus can be
interpreted as an external field in the language of directed percolation. This
analogy allows us to compute the crossover exponent and to predict the form of
the phase transition line close to its terminal point.Comment: 8 pages, 8 figure
Protecting, Enhancing and Reviving Entanglement
We propose a strategies not only to protect but also to enhance and revive
the entanglement in a double Jaynes-Cummings model. We show that such
surprising features arises when Zeno-like measurements are performed during the
dynamical process
A Flexible Implementation of a Matrix Laurent Series-Based 16-Point Fast Fourier and Hartley Transforms
This paper describes a flexible architecture for implementing a new fast
computation of the discrete Fourier and Hartley transforms, which is based on a
matrix Laurent series. The device calculates the transforms based on a single
bit selection operator. The hardware structure and synthesis are presented,
which handled a 16-point fast transform in 65 nsec, with a Xilinx SPARTAN 3E
device.Comment: 4 pages, 4 figures. IEEE VI Southern Programmable Logic Conference
201
Line-strength indices and velocity dispersions for 148 early-type galaxies in different environments
We have derived high quality line-strength indices and velocity
dispersions for a sample of 148 early-type galaxies in different
environments. The wavelength region covered by the observations
( to 6600 Ã…) includes the Lick/IDS indices
H, Mg1, Mg2, Mgb, Fe5015, Fe5270, Fe5335, Fe5406,
Fe5709, Fe5782, NaD, TiO1 and TiO2. The data are intended to
address possible differences of the stellar populations of early-type
galaxies in low- and high-density environments. This paper describes
the sample properties, explains the data reduction and presents the
complete list of all the measurements. Most galaxies of the sample
(85%) had no previous measurements of any Lick/IDS indices and for
30% of the galaxies we present first-time determinations of their
velocity dispersions. Special care is taken to identify galaxies with
emission lines. We found that 62Â per cent of the galaxies in the
sample have emission lines, as measured by the equivalent width of the
[OIII] 5007Å line, EW[OIII] > 0.3 Å
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